Mechanism for actuating the dipper stick of a power operated apparatus



May 16, 1967 J. P. WAITE 3,319,812

MECHANISM FOR ACTUATING THE DIPPER STICK OF A POWER OPERATED APPARATUS Filed Sept. 29, 1965 INVENTOR Jay/v R MIT! United States Patent MECHANISM FOR ACTUATING THE DIPPER STICK OF A POWER OPERATED APPARATUS John P. Waite, Menomonee Falls, Wis, assignor to .l. I.

Waite, Inc., Milwaukee, Wis., a corporation of Wiscousin Filed Sept. 29, 1965, Ser. No. 491,137 8 Claims. (Cl. 214138) This invention relates to a power operated excavating apparatus and more particularly to a mechanism for actuating the dipper stick of a back hoe.

In a conventional back hoe the dipper is usually actuated in the digging stroke by a cable which is attached to the forward portion of the dipper. By retrieving the cable the dipper is moved toward the machine and digs into the material to be excavated. The use of the drag cable attached to the dipper results in several difficulties in that the cable frequently is dragged over the rough edge of the excavation thereby causing undue abrasion of the cable. Secondly, due to the position of attachment of the cable to the dipper, it is difficult to dig closely to the machine for the cable interferes with the digging stroke.

In addition, as the digging force is dependent on the combined weight of the dipper and the boom the cable method of actuating the dipper tends to pull upwardly on the dipper so that the full weight of the machine will not be utilized in the digging stroke.

The present invention is directed to a novel apparatus for operating the dipper and provides an increased digging force over that obtainable by the conventional cable operated mechanism for actuating the dipper.

According to the invention, the dipper stick which carries the dipper is pivotally attached to the outer end of the boom. A pair of arms are connected between the upper end of the dipper stick and the boom and the arms are pivotally connected together by a shaft. A series of sheaves are mounted on the shaft which connects the arms and a second series of sheaves are mounted on the boom at a location between the end of the boom and the point of pivotal connection of the arm to the boom. A drag cable, which is coiled on a drum mounted on the cab of the machine, is reeved over the first and second series of sheaves and by retrieving the drag cable the first series of sheaves attached to the shaft is moved toward the second series of sheaves mounted on the boom to thereby extend the arms. Extending the arms moves the upper end of the dipper stick outwardly and correspondingly moves the dipper inwardly beneath the machine. By letting out on the drag cable, the sheaves are moved apart, causing the arms to scissor to a retracted position which thereby moves the upper end of the dipper stick toward the machine and moves the dipper away from the machine.

In a second embodiment of the invention a hydraulic cylinder is pivotally connected to the boom and the piston rod of the cylinder is connected to the shaft which pivotally joins the arms. By introducing hydraulic fluid into the upper end of the cylinder the piston rod is withdrawn, causing the arms to move to an extended position and thereby move the upper end of the dipper stick outwardly away from the machine. Conversely as hydraulic fluid is introduced into the lower end of the cylinder, the arms are scissored to a retracted position which causes the upper end of the dipper stick to move in a direction toward the machine.

With this construction there is no cable or sheaving system attached directly to the dipper in a position where it might interfere with the digging action of the dipper. This results in the present back hoe being capable of digging closely beneath the machine and also enables the 3,319,812 Patented May 16, 1967 dipper to undercut beneath pipes, boulders and the like without interference from cables.

For a given pull on the drag cable the digging force of the dipper can be conveniently varied by changing the number and reeving of the sheaves. This also enables the speed of digging to be varied for a given motor speed so that the motor'can be driven at the most efiicient speed and yet the speed of digging may be varied as desired. The use of the scissoring arms provides increased power at all positions or attitudes of the dipper stick. This is a distinct advantage over a hydraulic-actuated dipper stick in which a hydraulic cylinder interconnects the boom and the upper end of the dipper stick. In the conventional hydraulic unit of this type, when the piston rod is extended, the angle between the axis of the piston rod and the axis of the dipper stick is at a minimum with the result that the transmission of power is substantially reduced when the hydraulic cylinder is in the extended position. However, the present invention overcomes this difiiculty by employing a pair of arms which pivotally connect the boom and the upper end of the dipper stick. With this construction, even when the dipper stick is at an angle beneath the boom the power applied to the dipper stick will be substantial.

As a further advantage, the mechanism of the invention can be applied to existing back hoes with substantially little reconversion or alteration of the unit. Moreover, the dipper operating mechanism can be used in conjunction with the standard drag line construction which is connected directly to the dipper so that the operator can have his choice as to which mechanism he wishes to employ for a given digging operation. Furthermore, if the back hoe is set up to use both types of dipper operating mechanisms, in case of a malfunction of one of the mechanisms the other mechanism can be utilized so that down-time of the machine is substantially reduced or eliminated.

Other objects and advantages will appear in the course of the following description. The drawings illustrate the best mode presently contemplated of carrying out the invention.

In the drawings:

FIG. 1 is a side elevation of a back hoe utilizing the dipper operating mechanism of the invention;

FIG. 2 is a fragmentary side elevation, similar to FIG. 1, showing the dipper in a position beneath the boom.

FIG. 3 is a section taken along line 3-3 of FIG. 1;

FIG. 4 is a diagrammatic showing of the reeving of the sheaves;

FIG. 5 is a fragmentary side elevation of a modified form of the invention; and

FIG. 6 is a section taken along line 66 of FIG. 5. The drawings illustrate a power operated back hoe or drag shovel comprising a cab 1 which houses a drive mechanism and is mounted for rotation on crawlers or treads 2. A boom 3 is pivotally connected between a pair of lugs 4 which extend upwardly from the forward portion of the cab 1 and a dipper stick 5 is pivotally connected to the outer end of the boom.

The lower end of the dipper stick is secured to the rear edge portion of a dipper 6 and a pair of pitch braces 7 interconnect the dipper and the central portion of the dipper stick 5. The dipper stick 5, dipper 6 and pitch brace 7 are secured together in fixed relation to positively position the dipper with respect to the dipper stick. It is contemplated, however, that in some machines a wrist action dipper may be employed in which the dipper 6 is pivotally connected to the lower end of the boom and is power operated with respect to the dipper stick.

As shown in the drawings, the dipper 6 is of conventional construction and includes a pair of side plates 8 which are connected together by a generally curved bottom 9. The lower edge of the open end of the dipper is provided with a lip which carries a series of teeth 11 adapted to penetrate the material to be excavated.

According to the invention, a pair of arms 12 are pivotally connected to the upper end of the dipper stick 5 and a second pair of arms 13 are pivotally connected to the boom 3. The adjacent ends of arms 12 and 13 are pivotally mounted on a shaft 14. As best shown in FIG. 2, the ends of the arms 12 as well as the ends of the arms 13 straddle a sheave 15 which is rotatably mounted on the shaft 14. a

In addition to sheave 15 a second sheave 1 6 is mounted for rotation on the upper end of a mast 17 which is pivotally connected to the cab 1. A hoist line cable 18, which is secured to a drum 19 passes over the sheaves 16 and 15 and is dead ended on the mast 17. By retrieving the cable 18, the sheave 15 is moved toward the sheave 16, thereby pivoting the boom 3 upwardly about the forward portion of the cab 1, while letting out the cable 18 serves to pivot the boom 3 downwardly with respect to the cab 1.

A sheaving arrangement is employed to apply a force through the arms 12 and 13 to the upper end of the dipper stick 5 to pivot the dipper stick about the boom 3. The sheaving arrangement includes a pair of sheaves 20 mounted on a shaft 21 which is secured between brackets 22 attached to the boom 3. In addition to sheaves 20, a second pair of sheaves 23 are mounted on the shaft 14 on opposite sides of the arms 13. A drag cable 24 secured to drum 25 passes over a sheave 26 on boom 3 and is reeved about the sheaves 20 and 23 and is dead-ended on the bracket 22, best shown in FIG. 4. By retrieving the drag cable 24 the sheaves 23 are moved inwardly toward the sheaves 20 on the boom with the result that the arms 12 and 13 move to an extended position as shown in FIG. 2 to thereby move the upper end of the dipper stick outwardly away from the machine and move the dipper 6 inwardly toward the machine. Conversely, by letting out on the cable 24 the sheaves 23 move away from sheaves 20, causing the arms 12 and 13 to scissor or move to a retracted position, thereby moving the upper end of the dipper stick 5 toward the machine and moving the dipper 6 away from the machine.

FIGS. 5 and 6 illustrate a modified form of the invention. In this embodiment a hydraulic cylinder 27 is mounted within a slot 28 formed in the boom 3 and the lower end of the cylinder 27 is pivotally connected to a bracket 29 secured to the boom 3. A piston is slidably mounted within the cylinder and the piston rod 30 is provided with a forked end 31 which is pivotally connected to the shaft 14 on opposite sides of the sheave 15.

Hydraulic fluid is introduced into opposite ends of the cylinder 27 through lines 32 and 33.

The operation of the unit shown in FIGS. 5 and 6 is substantially similar to that shown in FIGS. 1-4. When hydraulic fluid is introduced into the upper end of the cylinder 27 through line 32, the piston rod is withdrawn thereby moving the arms 12 and 13 to the extended position as shown by the phantom lines in FIG. 5. Moving the arms to the extended position causes the upper end of the dipper stick 5 to move outwardly away from the machine with the result that the dipper 6 is moved inwardly toward the machine. By introducing hydraulic fluid into the lower end of the cylinder 27, the piston rod is extended thereby moving the arms 12 and 13 to the retracted position and moving the dipper 6 away from the machine.

The present invention operates the dipper by a force applied to the upper end of the dipper stick. With this construction the cables which are normally attached to the dipper are relocated. This enables the present back hoe to dig more closely beneath the machine as there is no danger of interference with the drag cable during digging. Furthermore, the relocation of the drag cable enables the dipper to dig and undercut in locations which were heretofore inaccessible for a conventional back hoe due to the interference from the normal drag cable.

By using the pair of pivotable arms 12 and 13 which connect the outer end of the boom to the upper end of the dipper stick and applying a force at the pivotal connection of the arms, a dipper operating mechanism is provided which enables a substantially uniform force to be applied to the dipper at all locations of the dipper stick with relation to the boom. This is a substantial advantage over the normal, hydraulic unit in which the force applied to the dipper is substantially reduced when the hydraulic cylinder is in an extended position and the dipper is at a location beneath the boom.

The dipper operating mechanism can be readily applied to standard or conventional back hoes with a minimum of reconstruction. Moreover, it is not necessary to remove the conventional drag line which is connected directly to the dipper and both mechanisms can be installed on a single back hoe. This gives the operator the option of using either dipper operating mechanism for any particular digging operation. This is a further advantage in the event one of the dipper operating mechanisms is broken down for the operator can then utilize the other mechanism with the result that down time for the machine is eliminated or substantially reduced.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

Iclaim:

1. In a power operated excavating apparatus, a supporting structure, a boom having one end pivotally connected to the supporting structure, a dipper stick pivotally attached at a position intermediate of its ends to the outer portion of the boom, a dipper secured to the lower portion of the dipper stick and adapted to penetrate into the material to be excavated, a first arm pivotally connected to the upper end of the dipper stick, a second arm pivotally connected to the boom, connecting means for pivotally connecting the arms together, and power means interconnecting the boom and said connecting means for moving said connecting means toward and away from the boom to thereby pivot the dipper stick with relation to the boom.

2. In a power operated excavating apparatus, a supporting structure, a boom having one end pivotally connected to the supporting structure, a dipper stick pivotally attached at a position intermediate of its end to the outer portion of the boom, a dipper secured to the lower portion of the dipper stick and adapted to penetrate into the material to be excavated, a first arm pivotally connected to the upper end of the dipper stick, a second arm pivotally connected to the boom, connecting means for pivotally connecting the arms together, and power means connecting said connecting means to said boom at a location between the pivotal connection of the dipper stick to the boom and the pivotal connection of said second arm to the boom to thereby move said connecting means toward and away from said boom and pivot the dipper stick with respect to the boom.

3. In a cable operated excavating apparatus, a supporting structure, a boom having one end pivotally connected to the supporting structure, a dipper stick pivotally attached at a position intermediate of its ends to the outer portion of the boom, a dipper secured to the lower portion of the dipper stick and adapted to penetrate into the material to be excavated, a first arm having its forward end connected to the upper end of the dipper stick, a second arm having its rear end connected to the boom, a shaft pivotally connecting the rear end of the first arm to the forward end of the second arm, and power means interconnecting the boom and the shaft at a location between the pivotal connection of the dipper stick to the boom and the pivotal connection of the second arm to the boom whereby the shaft is moved toward and away from said boom to thereby pivot the dipper stick about the boom.

4. In a cable operated excavating apparatus, a supporting structure, a boom having one end pivotally connected to the supporting structure, a dipper stick pivotally attached at a position intermediate of its ends to the outer portion of the boom, a dipper secured to the lower portion of the dipper stick and adapted to penetrate into the material to be excavated, a first arm having its forward end connected to the upper end of the dipper stick, a second arm having its rear end connected to the boom, a shaft pivotally connecting the rear end of the first arm to the forward end of the second arm, a first series of sheaves mounted on said shaft, a second series of sheaves mounted on the boom at a location between the pivotal connection of the dipper stick to the boom and the pivotal connection of the second arm to the boom, a cable reeved about said first and second series of sheaves, and means for exerting a force on the cable whereby movement of the cable in one direction causes the first series of sheaves to move toward the second series of sheaves to thereby pivot the dipper stick in one direction and movement of the cable in the opposite direction results in movement of the first series of sheaves away from the second series of sheaves to thereby pivot the dipper stick in the opposite direction with respect to the boom.

5. In a cable operated excavating apparatus, a supporting structure, a boom having one end pivotally connected to the supporting structure, a dipper stick pivotally attached at a position intermediate of its ends to the outer portion of the boom, a dipper secured to the lower portion of the dipper stick and adapted to penetrate into the material to be excavated, a first arm having its forward end connected to the upper end of the dipper stick, a second arm having its rear end connected to the boom, a shaft pivotally connecting the rear end of the first arm to the forward end of the second arm, a hydraulic cylinder extending within a vertical slot in said boom, means for pivotally connecting the lower end of said cylinder to said boom, piston means slidable within the cylinder, means for pivotally connecting the outer end of said piston means to said shaft, and means for supplying hydraulic fluid to said cylinder to move said piston means within the cylinder, movement of said piston means Within said cylinder causing said arms to pivot relative to each other and thereby pivot the dipper stick relative to the boom.

6. In a power operated apparatus, a supporting structure, a boom member having one end pivotally connected to the supporting structure, a working member pivotally attached at a position intermediate of its ends to the outer portion of the boom member, a first arm being pivotally connected to the boom member, a second arm being pivotally connected to the upper end of the working member, connecting means for pivotally connecting the arms together, and power means operably interconnecting one of said arms at a location spaced from the pivotal connection of that arm to the corresponding member and one of said members at a location spaced from the pivotal connection of that member to the corresponding arm, whereby the arms are moved at an angle with respect to each other by said power means to thereby pivot the Working member with respect to said boom member.

7. The apparatus of claim 6, in which the power means is a hydraulic cylinder.

8. In a power operated apparatus, a supporting structure, a boom member having one end pivotally connected to the supporting structure, a working member pivotally attached at a position intermediate of its ends to the outer portion of the boom member, a first arm being pivotally connected to the boom member, a second arm being pivotally connected to the upper end of the working member, connecting means for pivotally connecting the arms together, first sheave means connected to one of said arms at a location spaced from the pivotal connection of that arm with the corresponding member, second sheave means connected to one of said members at a location spaced from the pivotal connection of that member to the corresponding arm, a cable reeved about said first and second sheave means, and means for exerting a force on the cable whereby movement of the cable in one direction causes said first sheave means to move towards said second sheave means to thereby pivot said working member in one direction with respect to the boom member and movement of the cable in the opposite direction results in movement of said first sheave means away from said second sheave means to thereby pivot the working member in the opposite direction with respect to the boom member.

References Cited by the Examiner UNITED STATES PATENTS 1,823,137 9/1931 Fundom 214-138 2,812,872 11/1957 Perkins et al. 214-138X HUGO O. SCHULZ, Primary Examiner. 

1. IN A POWER OPERATED EXCAVATING APPARATUS, A SUPPORTING STRUCTURE, A BOOM HAVING ONE END PIVOTALLY CONNECTED TO THE SUPPORTING STRUCTURE, A DIPPER STICK PIVOTALLY ATTACHED AT A POSITION INTERMEDIATE OF ITS ENDS TO THE OUTER PORTION OF THE BOOM, A DIPPER SECURED TO THE LOWER PORTION OF THE DIPPER STICK AND ADAPTED TO PENETRATE INTO THE MATERIAL TO BE EXCAVATED, A FIRST ARM PIVOTALLY CONNECTED TO THE UPPER END OF THE DIPPER STICK, A SECOND ARM PIVOTALLY CONNECTED TO THE BOOM, CONNECTING MEANS FOR PIVOTALLY CONNECTING THE ARMS TOGETHER, AND POWER MEANS INTERCONNECTING THE BOOM AND SAID CONNECTING MEANS FOR MOVING SAID CONNECTING MEANS TOWARD AND AWAY FROM THE BOOM TO THEREBY PIVOT THE DIPPER STICK WITH RELATION TO THE BOOM. 